Punch and die assembly for making interlocking integral fasteners



ILLIAMs 2,924,312

l. A. W PUNCH AND DIE ASSEMBLY FOR MAKING INTERLOCKING INTEGRAL FASTENERS Original Filed NOV. 29. 1954 Feb. 9, 1960 I IN VEN TOR.

United States Patent() PUNCH AND DIE ASSEMBLY FOR MAKING IN- TERLOCKING INTEGRAL FASTENERS Ivan A. Williams, Portland, Oreg.

Original application November 29, 1954, Serial No. 471,808. Divided and this application December 23, 1957, Serial No. 710,832

5 Claims. (Cl. 189-36) ing Element and Method of Making the Same, and my U.S. Letters Patent 2,288,308, issued June 3.0, 1942 for Punch and Die. This application is a division of my abandoned application Serial No. 471,808, filed November 29, 1954.

rl`he aforesaid Letters Patent disclose a method of uniting overlying sheets of material by means of a punch and die which operate to form spaced incisions entirely through both thicknesses of the material. Next the sections of the material between the incisions are deformed in the direction of motion of the advancing punch until substantial portions lie beyond the plane of that surface of the material which is adjacent the die. This deformation is accompanied by stretching and bending portions of the material at the end zones between the spaced incisions in a pattern conforming to the shape of the punch.

The central sections of the deformed portions then are pressed against the anvil of the die by the punch with the result that they are swaged and extruded laterally. In this manner there are formed laterally extending edges which span the incisions and underlie the undisplaced material on each side thereof, preventing retraction of the displaced material through the opening 'between the incisions. This locks the pieces together.

Although the resulting fastener resists separation of the overlying pieces of material by a force exerted perpendicular to the plane of the material and by a force exerted in a plane parallel to the plane thereof but transversely of the fastener, it does not resist to so great an extent their separation by the application of a force exerted in the plane of the material but longitudinally of the fastener.

In other words, if a sufficiently great force is applied longitudinally of the fastener, the overlying displaced section may be slipped along the underlying displaced section, thereby separating the pieces. For example, if a force of 2000 pounds is required to separate the pieces when applied in a direction normal to the plane thereof, a force of about 1100 pounds may be sucient to separate them if it is applied in the plane of the pieces but longitudinally of the fastener.

Accordingly, it is the primary object of the present invention to provide an integral fastener for overlying pieces of material, which fastener has substantially increased resistance to force applied in a direction longitudinally of the fastener.

It is another object of the-present invention to provide an integral fastener for uniting overlying pieces of material which may be formed lwith minimum thinning 'of the material and which, as a result, is of increased strength.

Still another object of this invention is the provision of an integral fastener for uniting overlying pieces of material which is characterized by the presence of interlocking edges which lock the pieces together so that they are resistant to separation by a force applied from any direction.

Still another object of this invention is the provision of a method of forming an integral, interlocking fastener for uniting overlying pieces of material which method may be carried out rapidly and eiiiciently.

The manner in which the foregoing and other objects of this invention are accomplished will be apparent from the accompanying specitication and claims considered `together with the drawings, wherein:

Figure 1 is a view in end elevation of a punch and die which may be used for forming the presently described fastener; Y

Figure 2 is a view in side elevation of the punch and die of Figure 1;

Figure 3 is an end view of the die of Figures 1 and 2 as viewed from the line 3 3 of Figure 2;

Figure 4 is a plan view of the interlocked fastener which is produced by the operation of the punch and die of Figures l-3;

Figure 5 is a longitudinal sectional view of the fastener of Figure 4 taken along the line 5 5 of that ligure;

Figure 6 is a transverse sectional view of the fastener of Figure 4 taken along the line 6--6 of that ligure; and

Figures 7 and 8 are plan v1ews of alternate forms of fasteners which may be produced by the presently described method.

Broadiy stated, the presently described method for forming an integral fastener through overlying pieces of material comprises first forming laterally spaced apart, substantially aligned incisions through the pieces, the distance between selected opposite segments of the incisions being greater than that between other opposite segments thereof. For example, the incisions may be outwardly offset so that the distance between the central segments thereof will be greater than that between the terminal segments.

'l'he material between the incisions then is bent until the displaced portion of one of the pieces lies beyond the outer surface of the other of the pieces. The displaced portion next is spread laterally until it underlies the adjacent surface, thereby interlocking the pieces through a plurality of interengaging edge surfaces.

Considering the foregoing in greater detail and with particular reference to the drawings:

A punch and die assembly which may be employed in forming the presently described fastener is illustrated in Figures l-3. As is apparent, the assembly comprises a die member and a punch member. Plhe die member includes a body 10, one end of which is formed with a pair of spaced apart shoulders 12, 14. This end lof the die body also has a pair of spaced apart recesses 16, 18 lying p outside of the shoulders and a central longitudinal opening 20. An anvil 22 is connected to the body of the die,

as by being frictionally received in longitudinal opening 20 of the die body. 1t has a work surface 24 and a pair of opposite side faces 26, 28 formed with outwardly extending projecting portions 30, 32 respectively. The

latter may extend the full length of the anvil.

Positioned against side faces 26, 28 respectively of the anvil are cutting elements 34, 36. These are formed with recesses 38, 40 which are complementary to projections 30, 32 on the anvil. The inner ends of the cutters abut against shoulders 12, 14 of the die body. Their outer ends, on which are the cutter surfaces 42, 44, extend a spaced distance beyond the work surface 24 of the anvil, this distance being predetermined to accommodate the particular thickness of the material which is to be theV subject matter of the fastening operation.

Means are provided for maintaining cutters 34, 36 pressing resiliently against the side' `faces of the anvil and for releasably securing them tothe die body. A preferred means of accomplishing these functions comprises attaching the cutters to resilient tongues 46, 50. The latter preferably are formed integrally with the cutters, as by recessing the latter at 52, 54 and forming the material defined in part by the recesses into outwardly bowed tongues in Vthe manner indicated.

This in effect accomplishes attaching the tongues to the central portion o f the cutters, which in turn makes possible abutting the inner edges of the cutters against shoulders 12, 14 of the die body while contemporaneously providing arcuate spring members which may be in- Y serted into recesses 16, :18, therein.` These frictionally engage the side walls of the recessesand secure the cutters to the body of the die, while maintaining them `pressing yieldably against the side faces of the anvil.

The punch sectionV of the assembly which cooperates withv the die in forming fasteners through the, Aoverlying pieces of material includes a body portion 60 and a punch portion 62. The latteris formed with a working surface 64, angular forming sections 66, 68 and longitudinal projections 70, 72 along its opposite side faces. The configuration of the working surface of the punch thus conforms generally to that of the working surface of the anvil.

' Operation v The manner in which the above described punch and die cooperate in forming the novel fastener of the present invention will be apparent from a consideration of Figures 4 6.

First, overlying pieces of material, for example, sheets of aluminum 80, 82 are placed between the punch and die. The punchthen is advanced towards the die whereupon its forms a pair of laterally spaced apart, substantially aligned incisions completely through the overlying pieces of material. The pattern of these incisions is particularly apparent from Figure 4. Y

As will be seen from that figure, one pai-r of overlying incisions comprises the outer segment 84, 86 and a central,

outwardly offset segment 88. These segments are inter` connected by the angled connecting segments 90, 92, the angle preferably being about 45. The configuration of the companion pair of overlying incisions is similar. Accordingly, it is made up of vthe terminal segments V94, 96 and the outwardly offset, central segment 98, these being interconnected by the connecting segmentV 100, 102.

The pattern of the incisions may be varied however, by

using punches and dies of Vdifferent' configurations, provided a pattern is retained in` which the distance between selected opposite segments of the incisions is greater than that between other opposite segments thereof. Thus the pattern of the incisions may be as is illustrated in Figure 7. In this pattern one of the incisions is made up of terminal segments 104, 106 and a central segment 108, the companion incision being composed of terminal segments 110, 112I and the central segment 114. In this embodiment, the pairs 104, 110 and 106,` 112 of the terminal segments are angled slightly toward each other, while the central segmentsA 108, 114' are maintained substantially parallel.

Similarly the incisions may assume the `pattern o-f Figure 8. In this. configuration the central segments of the incisions are inwardly offset. Thus` one of the incisions comprises the terminal Vsegments 116, 118, the central. segment 120 and the connecting segments 122, 124` The other incision is4 complementary, being made up of the terminal segments 126, 128, the inwardly oiset itralsegment 130 and the Aconnecting segments 132, Referring again to the embodiment of Figures 4 6, contmuedadvancement of the punch causes displaQQmGIlt, f

. edges 90,92 and 100,102 resist separation of the pieces force.l -For example, if an integral 'fastener not having the presently described interlock will withstand a lateral force of 2000. pounds and a longitudinal force of about the material betweenA the spaced incisions until sections 140, 142 are completely displaced below the plane of the bottom surface of the underlying sheet 82. During this process the end sections of the material between the spaced incisions are stretched and deformed to conform to the configuration of theforming surfaces 66, 68 of r the punch.

lFurther advancement of the punch causes the swaging and lateral extrusion of `the displaced material against the anvil, the cutters 34,36 moving outwardly against the tension of resilient members 46, V50 attached thereto as required to accommodate the extruded material. As a result there are formed laterally extending edges 144,`

146 indicated in dotted outline in Figure 4, which fasten the sheets together.

As a result of the foregoing operation there is formed a fastener which is strong in alldirections because of the presence of the'interlocking edges ofthe incised and displaced material.. Thus edges 144,V `146 resist lateral separation ofthe pieces as well as separa-tion by a force exerted in the plane of the fastener, but normall to the longitudinal axis thereof. Also, the interlocked angular by a force exerted .in the plane of the `fastener but in a directionlongitudinally of the axis thereof.

Accordingly the fastener is of substantial strength irrespective of the directionof application of a disrupting 1100 pounds without breaking, a fastener ofthe presently described class which will withstand a lateral force of 2000 pounds will withstand a longitudinal force of about 1900 pounds. Hence the longitudinal strength of the vfastener has been increased by about 70% and its usefulness augmented accordingly'.

It is to be understood that .the form` of my invention, herewith shown and described, is -to be taken as a pre- `ferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of my invention, or the scope of the subjoined claims. Thus although a particular form of mounting the cutters on the diehas been described herein, this may be modified in accordance with disclosures contained `in my various U.S; patents including U.S. 2,254,558 and 2,288,308-, these pertaining to methods for forming integral fasteners of the class described herein and to apparatus for. forming: the same.

Having now described my invention, I claim:

l. A fastener-for uniting overlying pieces of material which comprises integral portions of the pieces defined` ments, the distancebetween a pair of selected opposed segments of the incisions being greater than that between the other opposed segments, said portions being dis-` i placed so that the displacedfportion of one of the pieces lies beyond the plane of the outer surface of the other of` the pieces, the displacedportion of `said one of the pieces` being. spread laterally until its margins underlie thesaid other ofthe pieces, thereby securely interlocking the piecesandl preventing their separation.

2. A fastener for` uniting overlying pieces of material which comprises integral portions' of the pieces defined by a pair of laterally spaced apart, substantially aligned incisions through the pieces, each of the incisions comprising' an" intermediate segmentand terminal segments` connected 4"thereto, the terminal `"segments beingsubsta'ntially parallel to the intermediatey segment, the intermediate' segment of at leastonerof the incisions being offset `from the terminalfsegments, thereof, said portions being displaced sio'that the displaced portion of one of thapieces lies beyondthe plane of the outersurface of the other of the pieces, theV displaced portion of said one of the pieces being spread laterally until its margins underlie the said other of the pieces, thereby securely interlocking the pieces and preventing their separation.

3. A fastener for uniting overlying pieces of material which comprises integral portions of the peces dened by a pair of laterally spaced apart, substantially aligned incisions through the pieces, each of the incisions comprising an intermediate straight-line segment and terminal straight-line segments connected thereto, the terminal segments being substantially parallel to the intermediate segment, the intermediate segments of both of the incisions being outwardly offset from the terminal segments thereof, said portio-ns being displaced so that the displaced portion of one of the pieces lies beyond the plane of the outer surface of the other of the pieces, the displaced portion of said one of the pieces being spread laterally until its margins underlie the said other of the nieces, thereby securely interlocking the pieces and preventing their separation.

4. The method of uniting overlying pieces of material through an integral fastener which comprises forming a pair of laterally spaced apart substantially aligned incisions through the pieces with each of the incisions having an intermediate segment and terminal segments connected thereto in parallel relation, the intermed'ate segment of at least one of said incisions being oiset from the terminal segments thereof, deforming the material between the incisions outwardly until the displaced portion of one of the pieces lies beyond the outer surface of the other of the pieces, spreading the displaced portion of said one of the pieces until it underlies the outer surface of the other of the pieces, thereby securely interlocking the pieces and preventing their separation.

5. The method of uniting overlying pieces of material through an integral fastener which comprises forming a pair of laterally spaced apart substantially aligned incisions through the pieces with each of the incisions having an intermediate segment and terminal segments connected thereto in parallel relation, the intermediate segments of both of the incisions being outwardly oiset from the terminal segments thereof, deforming the material between the incisions outwardly until the displaced portion of one of the pieces lies beyond the outer surface of the other of the pieces, spreading the displaced portion of said one of the pieces until it underlies the outer surface of the other of the pieces, thereby securely interlocking the pieces and preventing their separation.

References Cited in the le of this patent UNITED STATES PATENTS 56,494 Gordon July 17, 1866 977,178 Ferguson Nov. 29, 1910 2,288,308 Williams June 30, 1942 2,426,670 Cooley Sept. 2, 1947 

